Brazilian President Luiz Inácio Lula da Silva has won an unprecedented fourth term, defeating far-right Senator Flávio Bolsonaro in Sunday's runoff with 51.8% of the vote to 48.2%, a lead of nearly 4.4 million votes.

The result is a double record: no president in Brazil or Latin America has won a fourth term, and no first-round runner-up has gone on to win the runoff since Brazil's return to democracy in 1985.

Lula, who turns 81 on Tuesday, lost the first round to Bolsonaro by more than 2.2 million votes three weeks earlier.

The comeback defied polls, precedent and global anti-incumbent sentiment.

According to CNN, Lula added more than 10 million votes between the rounds while Bolsonaro gained just 3.6 million, and he flipped Minas Gerais — swinging roughly 690,000 votes in the margin — after losing it by nearly 590,000 in the first round.

Flávio Bolsonaro refused to concede and said he would seek to annul the election, citing a Supreme Court decision to extend voting by two hours after Lula's campaign complained that buses were pulled from circulation in cities that favor him.

Bolsonaro's own campaign had also requested extensions in southern states hit by heavy rain, and legal experts told the outlets the complaint faces a high bar. His father, Jair Bolsonaro, similarly refused defeat in 2022 before being convicted of plotting a coup and sentenced to 27 years.

The victory halts a wave of right-wing wins aligned with Donald Trump across Latin America, including Argentina's Javier Milei, Chile's José Antonio Kast, Ecuador's Daniel Noboa and Colombia's Abelardo de la Espriella.

CBC reports the result means Latin America's largest economy will likely keep defying Trump's demands despite increased US tariffs, while Lula declared in his speech: "This country will not accept being anyone's backyard."

Mexican President Claudia Sheinbaum congratulated him, writing "Long live democracy, the people of Brazil won."

The historic win comes with limited room to govern. According to France 24, Brazil elected its most conservative Congress since the 1980s, with public debt above 82% of GDP and growth forecast at just 2.3% next year, while nearly half of Brazilians told a Quaest poll the economy had worsened.

Cost-of-living dissatisfaction and security demands will test Lula's negotiating skill.

He pledged to regulate big tech platforms after his campaign accused Meta of favoring Bolsonaro, and plans a Ministry of Public Security, per DW's live coverage.

Analysts told CNN he will likely avoid regional integration pushes and instead exercise leadership through Brazil's economic weight, while closely watching the US midterm elections, where Republican losses could improve his position against Washington's pressure.